Regulator circuits are used in semiconductor devices to provide a stable DC (Direct Current) output voltage with little fluctuation to a load. Such regulators are also known as Low Drop Out (LDO) regulators. Typically, LDO regulators rely on feedback voltage to maintain a constant output voltage. That is, an error signal whose value is a function of the difference between the actual output voltage and a nominal value is amplified and used to control current flow through a pass device such as a power transistor, from the power supply to the load. The drop-out voltage is the value of the difference between the power supply voltage and the desired regulated voltage. Most LDO regulators also include a bypass capacitor coupled to the load to ensure a stable output voltage.
The low drop out nature of the regulator makes it useful in portable devices such as cameras, which have a battery power supply. Oftentimes the bypass capacitor must have a large capacitance to ensure stable operation. However, the use of such a large capacitor is costly and impacts integration of the regulator circuit on a chip. Thus, there is a need for an on-chip, capacitor free regulator.